Question

A rectangle lot 30m by 20m is surronded on all four sides by a concrete walk 3m wide. If you need to concrete only the sidewalk, how much concrete will you need? (surface area)

Answer 1

The length of the rectangle is 30 m

The width of the rectangle is 20 m

The sidewalk is 3m wide on all sides, so

length of sidewalk = 30+6 =36 m

Width of sidewalk = 20+6 = 26 m

Area of rectangle =
`length*width`

Area of rectangle =
`30*20=600`

Area of rectangle including sidewalk =
`36*26=936`

Hence, area of sidewalk alone = area of rectangle with sidewalk - area of rectangle

Surface Area =
`936-600=336` m²